On 05.08.19 17:09, Vladimir Sementsov-Ogievskiy wrote: > 05.08.2019 17:55, Max Reitz wrote: >> In write-blocking mode, all writes to the top node directly go to the >> target. We must only mirror chunks of data that are aligned to the >> job's granularity, because that is how the dirty bitmap works. >> Therefore, the request alignment for writes must be the job's >> granularity (in write-blocking mode). >> >> Unfortunately, this forces all reads and writes to have the same >> granularity (we only need this alignment for writes to the target, not >> the source), but that is something to be fixed another time. >> >> Cc: [email protected] >> Signed-off-by: Max Reitz <[email protected]> >> --- >> v2: Fix the placement of our bdrv_refresh_limits() call [Vladimir] >> --- >> block/mirror.c | 25 +++++++++++++++++++++++++ >> 1 file changed, 25 insertions(+) >> >> diff --git a/block/mirror.c b/block/mirror.c >> index 8cb75fb409..7f0ff01beb 100644 >> --- a/block/mirror.c >> +++ b/block/mirror.c >> @@ -1481,6 +1481,15 @@ static void >> bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, >> *nshared = BLK_PERM_ALL; >> } >> >> +static void bdrv_mirror_top_refresh_limits(BlockDriverState *bs, Error >> **errp) >> +{ >> + MirrorBDSOpaque *s = bs->opaque; >> + >> + if (s && s->job && s->job->copy_mode == >> MIRROR_COPY_MODE_WRITE_BLOCKING) { >> + bs->bl.request_alignment = s->job->granularity; >> + } >> +} >> + >> /* Dummy node that provides consistent read to its users without requiring >> it >> * from its backing file and that allows writes on the backing file chain. >> */ >> static BlockDriver bdrv_mirror_top = { >> @@ -1493,6 +1502,7 @@ static BlockDriver bdrv_mirror_top = { >> .bdrv_co_block_status = bdrv_co_block_status_from_backing, >> .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, >> .bdrv_child_perm = bdrv_mirror_top_child_perm, >> + .bdrv_refresh_limits = bdrv_mirror_top_refresh_limits, >> }; >> >> static BlockJob *mirror_start_job( >> @@ -1637,6 +1647,21 @@ static BlockJob *mirror_start_job( >> s->should_complete = true; >> } >> >> + /* >> + * Must be called before we start tracking writes, but after >> + * >> + * ((MirrorBlockJob *) >> + * ((MirrorBDSOpaque *) >> + * mirror_top_bs->opaque >> + * )->job >> + * )->copy_mode >> + * >> + * has the correct value. >> + * (We start tracking writes as of the following >> + * bdrv_create_dirty_bitmap() call.) >> + */ >> + bdrv_refresh_limits(mirror_top_bs, &error_abort); > > Also, I'm not sure about error_abort() here. why not use local_err and return > NULL > if failed?
Why would it fail?
Max
>> +
>> s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL,
>> errp);
>> if (!s->dirty_bitmap) {
>> goto fail;
>>
>
>
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